1. Field of the Invention
The present invention relates to an agent system including a plurality of agents. In particular, the present invention relates to an agent system of the knowledge propagation type, which realizes the intermediation and propagation of knowledge among a plurality of agents with good consistency by exchanging messages.
2. Description of the Related Art
In recent years, due to the remarkable development of computer networks such as the Internet, it is becoming possible that a user gets access to a plurality of databases at physically different places through a computer network.
However, with the increase in scale of computer networks, the number of accessible databases also increases, and the downside of this is that it becomes difficult for a user to know in which database on the computer network desired information is stored. Furthermore, procedures for utilizing databases are not standardized, so that a user has the inconvenience of having to learn a procedure for each database.
For example, in the case of the Internet, as primitive methods for finding information (pages) desired by a user, there are methods for browsing links one by one and methods for displaying a great amount of information (pages) in a hit list obtained by keyword searching one by one. However, with any of these methods, a great amount of time is required for obtaining desired information, which becomes a burden on the user""s time and patience.
Therefore, methods have been proposed for storing a program called an agent on the computer network so as to mediate between a user and a database.
More specifically, a conventional agent system has a plurality of software programs which function as autonomous modules, called software agents (hereinafter, referred to as xe2x80x9cagentsxe2x80x9d). When a user searches for desired information, the user is not required to conduct keyword searching such as the browsing of links; instead, an agent which has received an instruction from the user cooperates with another agent to collect specified information from the network. In order for agents to communicate with each other for cooperation, common languages between agents, such as ACL (Agent Communication Language), have been defined.
However, in the above-mentioned conventional agent system, an agent directly sends a message in response to a question sent by another agent, and a knowledge propagation system is established only in a one-to-one relationship between two agents.
Therefore, with the increase in scale of the network, the agent system is becoming large and complicated. This causes the number of agents to increase and a common language between agents to be diversified. As a result, it is becoming difficult to propagate knowledge between agents with good consistency.
The present invention has been achieved in order to solve the above-mentioned problems, and its objective is to provide a facilitating agent apparatus and an agent system in which each facilitating agent apparatus is allowed to appropriately convert and propagate knowledge transmitted from another facilitating agent, thereby conducting intermediation and propagation of knowledge among a plurality of agents with good consistency.
In order to achieve the above-mentioned objective, a facilitating agent apparatus of the present invention for allowing a message to be exchanged among a plurality of agents, includes: a message transmission/receiving section for transmitting/receiving a message to/from another agent apparatus; a meta-knowledge storing section for accumulating meta-knowledge; and a message processing section for converting a received message based on the meta-knowledge, so as to create a retransmission message for transmitting a content of the received message to another agent apparatus.
According to the above-mentioned structure, knowledge contained in a received message is not transferred as it is to another facilitating agent apparatus. Instead, the knowledge contained in a received message is appropriately converted based on meta-knowledge containing information such as a content of a message which has been received in the past and a transmission target of a message, and transmitted to another facilitating agent apparatus. Thus, a facilitating agent apparatus can be provided, which is capable of propagating knowledge among a plurality of facilitating agent apparatuses with good consistency.
The facilitating agent apparatus further includes a message conversion section for abstracting knowledge contained in the received message, so as to create knowledge to be contained in the retransmission message.
According to the above-mentioned structure, the retransmission message contains knowledge created by abstraction (i.e., replacement of a content of a received message by a superior concept). Therefore, a facilitating agent apparatus can be provided, which is capable of propagating knowledge more efficiently, compared with a facilitating agent apparatus which transfers a received message as it is.
It is preferable that the facilitating agent apparatus further includes an ontology transformation section for transforming ontology of knowledge contained in a received message to another ontology, so as to create knowledge to be contained in the retransmission message.
According to the above-mentioned structure, the ontology of knowledge contained in the received message can be transformed to another ontology, so that knowledge expressed by different ontology can be shared by a plurality of facilitating agent apparatuses. Thus, even when the number, type, or the like of facilitating agent apparatuses increases along with an increase in scale of a system, a facilitating agent apparatus can be provided which is capable of propagating knowledge with good consistency.
Preferably, the meta-knowledge contains information regarding relationship between the received message and the retransmission message. It is also preferable that the facilitating agent apparatus further includes a denying message processing section for creating a denying message for denying knowledge of a transmitted message, and the denying message processing section refers to the information when receiving a denying message for denying knowledge of a previously received message and creates a denying message for denying knowledge contained in a retransmission message transmitted in response to the received message.
According to the above-mentioned structure, since the denying message processing section is provided, it becomes possible to deny own-knowledge, which has already been transmitted to another facilitating agent apparatus. Furthermore, if the denying message processing section receives a denying message for denying knowledge, which has already been transmitted, from another facilitating agent apparatus, the denying message processing section transmits a denying message for denying a retransmission message with respect to facilitating agent apparatuses to which the agent has transmitted its knowledge through the retransmission message. Thus, the knowledge serially propagated among a plurality of facilitating agent apparatuses can be successively denied. Accordingly, even if propagated knowledge is denied, consistency of knowledge can be kept among a plurality of facilitating agent apparatuses.
It is preferable that the facilitating agent apparatus further includes a knowledge storing section for storing the knowledge of the facilitating agent apparatus; and an own-knowledge transmission message creating section for creating a message for transmitting knowledge stored in the knowledge storing section to another facilitating agent apparatus.
According to the above-mentioned structure, the facilitating agent apparatus stores each intrinsic knowledge in the knowledge storing section, and is capable of propagating the knowledge to another facilitating agent apparatus, if required. Because of this, knowledge of each facilitating agent apparatus can be propagated to the entire system with good consistency.
Furthermore, in order to achieve the above-mentioned objective, an agent system of the present invention includes a plurality of facilitating agent apparatuses and propagates knowledge among the facilitating agent apparatuses, wherein each of the facilitating agent apparatuses includes a message transmission/receiving section for transmitting/receiving a message to/from another facilitating agent apparatus; a meta-knowledge storing section for accumulating meta-knowledge; and a message processing section for converting a received message based on the meta-knowledge, so as to create a retransmission message for transmitting a content of the received message to another facilitating agent apparatus.
According to the above-mentioned structure, knowledge contained in a message which each facilitating agent apparatus has received is not transferred as it is to another facilitating agent apparatus. The knowledge contained in a message is appropriately converted, for example, based on meta-knowledge containing information such as a content of a message which has been received in the past and a transmission target of a message, and is transmitted to another facilitating agent apparatus. Thus, an agent system can be provided, which is capable of propagating knowledge with good consistency.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.